They rent a farm for $4.00 per month. According to MeasuringWorth.com, in 2015 the relative worth of $4.00 from 1940 was:
In 2015, the relative wage or income worth of $4.00 from 1940 is:
-------$137.00, using the unskilled wage
-------$182.00, using the Production Worker Compensation
-------$288.00, using the nominal GDP per capita